1. Field of the Invention
The present invention relates to a compressor used in an air conditioning system for a car, and more particularly, to a variable capacity swash plate type compressor which changes the capacity of discharge by adjusting the pressure of a crank chamber.
2. Description of the Related Art
In general, swash plate compressors include fixed capacity type swash plate compressors and variable capacity swash plate type compressors according to use. Variable capacity swash plate type compressors among them change the angle of inclination of a swash plate by using a control valve depending on a change in load and control the quantity of transportation of a piston to achieve precise control, and simultaneously change an angle of inclination continuously to reduce a rapid change in torque of an engine due to the compressor so that the feeling of smoothly riding a car can be increased.
FIG. 1 is a cross-sectional view of a conventional variable capacity swash plate type compressor.
As illustrated in FIG. 1, the conventional variable capacity swash plate type compressor comprises a cylinder block 12 in which a plurality of cylinder bores 12a are formed, a front housing 11 which is sealed and connected to the front side of the cylinder block 12, and a rear housing 13 which is sealed and connected to the rear side of the cylinder block 12 by interposing a valve unit 14 between the cylinder block 12 and the rear housing 13.
A crank chamber 15 is formed inside the front housing 11. One side of a driving shaft 16 is rotatably supported near the center of the front housing 11. The other end of the driving shaft 16 passes the crank chamber 15 and is rotatably supported by the cylinder block 12.
A rotor 23 and a swash plate 24 are installed on the driving shaft 16, and a spring 25 for elastically supporting the swash plate 24 is interposed between the rotor 23 and the swash plate 24.
A ball 26 is formed at one side of the swash plate 24. Thus, as the rotor 23 rotates, the ball 26 of the swash plate 24 is moved to be slid in a guide hole of the rotor 23, and an angle of inclination of the swash plate 24 is changed. In addition, pistons 21 are inserted by inserting a shoe 27 in the outer peripheral face of the swash plate 24 and make a reciprocating motion within each of the cylinder bores 12a of the cylinder block 12.
Each of a suction chamber 31 and a discharge chamber 32 is formed in the rear housing 13. The suction chamber 31 and the discharge chamber 32 are connected to an outside of the compressor via an external refrigerant circuit (not shown).
Meanwhile, an oil separator 39 is installed at the rear end of the driving shaft 16 and is encompassed by an oil chamber 40. A communication hole 42 connecting the crank chamber 15 and the oil separator 39 is formed in the driving shaft 16. The oil separator 39 is formed in the form of a cylindrical cap.
When the compressor operates, the pressure of the crank chamber 15 is changed (for example, from a low pressure to a high pressure) according to manipulation of the control valve 38 so that a refrigerant remaining in the crank chamber 15 is exhausted toward the suction chamber 31 via the oil separator 39 along the communication hole 42 of the driving shaft 16. A refrigerant gas passing the oil separator 39 and being near an inner circumference of the oil separator 39 rotates together with the oil separator 39. Oil in a mist phase that exists in the refrigerant gas is centrifugally separated from the refrigerant gas.
The oil that is centrifugally separated by the oil separator 39 in this manner is attached to the inner circumference of the oil separator 39 and is moved to be slid toward the rear end of the oil separator 39. The oil is exhausted to the outside through a gap between the front end of the oil separator 39 and the vale unit 14 or a trough portion 39b and stays in the oil chamber 40.
In addition, the oil is continuously induced to an air supply passage 37 through a communication passage 40a and is returned to the crank chamber 15 by using a refrigerant gas etc.
However, according to the conventional variable capacity swash plate type compressor, an additional oil separator 39 is needed, and a space for installing the oil separator 39 is required. Thus, there is a limitation in designing and assembling the compressor. Furthermore, oil passes the communication passage 40a of the driving shaft 16, the suction chamber 31, and the air supply passage 37 etc. sequentially together with a refrigerant so that loss of oil due to a long flow path occurs inevitably.